Find the median in c++

// C++ implementation of randomized quickSelect
#include<iostream>
#include<climits>
#include<cstdlib>
using namespace std;

int randomPartition(int arr[], int l, int r);

// This function returns k'th smallest element in arr[l..r] using
// QuickSort based method. ASSUMPTION: ELEMENTS IN ARR[] ARE DISTINCT
int kthSmallest(int arr[], int l, int r, int k)
{
	// If k is smaller than number of elements in array
	if (k > 0 && k <= r - l + 1)
	{
		// Partition the array around a random element and
		// get position of pivot element in sorted array
		int pos = randomPartition(arr, l, r);

		// If position is same as k
		if (pos-l == k-1)
			return arr[pos];
		if (pos-l > k-1) // If position is more, recur for left subarray
			return kthSmallest(arr, l, pos-1, k);

		// Else recur for right subarray
		return kthSmallest(arr, pos+1, r, k-pos+l-1);
	}

	// If k is more than number of elements in array
	return INT_MAX;
}

void swap(int *a, int *b)
{
	int temp = *a;
	*a = *b;
	*b = temp;
}

// Standard partition process of QuickSort(). It considers the last
// element as pivot and moves all smaller element to left of it and
// greater elements to right. This function is used by randomPartition()
int partition(int arr[], int l, int r)
{
	int x = arr[r], i = l;
	for (int j = l; j <= r - 1; j++)
	{
		if (arr[j] <= x)
		{
			swap(&arr[i], &arr[j]);
			i++;
		}
	}
	swap(&arr[i], &arr[r]);
	return i;
}

// Picks a random pivot element between l and r and partitions
// arr[l..r] arount the randomly picked element using partition()
int randomPartition(int arr[], int l, int r)
{
	int n = r-l+1;
	int pivot = rand() % n;
	swap(&arr[l + pivot], &arr[r]);
	return partition(arr, l, r);
}

// Driver program to test above methods
int main()
{
    int n;
	cin >> n;
    int a[n];
for (int i = 0; i <n; ++i)
{
    cin >> a[i];
}
	int  k = (n+1)/2;
	cout << "" << kthSmallest(a, 0, n-1, k);
	return 0;
}